1996 Grand AM security Light Headache

[theone6800]

Hello I have a 1996 grand am se with a 3.1 engine. Motor went bad so I replaced it, I know the motor is good cause I heard it running in the previous car which had only 50k miles. Ok now the problem: car starts fine but dies after 2 to 3 seconds. Checked fuel pumps injectors etc. everything works fine. Mechanic looked over it and said it was the security theft on the car that shuts down the car it needs to go to the dealer for reprogramming.Called bout 7 dealers to be let down by them telling me the car is to old they dont work on cars 10 years or older. Did a lot of research online found alot of people with simular problems but none like mine.Things I've tried: multiple hours with the bump key wait 10 to 20 minutes trick to no success. Also instead of the security light flashing like others mines just stay solid which the mechanic said was odd he also checked for coroded wires and tried changing the computer with no success security light still stays on solid with no blinking and runs for 2 to 3 secs then dies. Any help is greatly appreciated....